Unraveling the aging dynamics in the simultaneous immobilization of soil metal(loid)s using oxides

Wenjing Zong; Liuwei Wang; Xiaoxiang Wang; Xiaoguo Geng; Yufei Lian; Huixia Wang; Renjie Hou; Jing Guo; Xiaodong Yang; Deyi Hou

doi:10.1016/j.scitotenv.2023.167220

Unraveling the aging dynamics in the simultaneous immobilization of soil metal(loid)s using oxides

Sci Total Environ. 2023 Dec 20:905:167220. doi: 10.1016/j.scitotenv.2023.167220. Epub 2023 Sep 19.

Authors

Wenjing Zong¹, Liuwei Wang¹, Xiaoxiang Wang², Xiaoguo Geng³, Yufei Lian¹, Huixia Wang¹, Renjie Hou⁴, Jing Guo¹, Xiaodong Yang¹, Deyi Hou⁵

Affiliations

¹ School of Environment, Tsinghua University, Beijing 100084, China.
² School of Environment, Tsinghua University, Beijing 100084, China; Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
³ School of Environment, Tsinghua University, Beijing 100084, China; Wyoming Seminary, 201 N Sprague ave, Kingston, PA 18704, United States.
⁴ School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin 150030, Heilongjiang, China.
⁵ School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: houdeyi@tsinghua.edu.cn.

PMID: 37734613
DOI: 10.1016/j.scitotenv.2023.167220

Abstract

Immobilization represents the most extensively utilized technique for the remediation of soils contaminated by heavy metals and metalloids. However, it is crucial to acknowledge that contaminants are not removed during this process, thereby leaving room for potential mobilization over time. Currently, our comprehension of the temporal variations in immobilization efficacy, specifically in relation to amendments suitable for industrial sites, remains very limited. To address this knowledge gap, our research delved into the aging characteristics of diverse oxides, hydroxides, and hydroxy-oxides (collectively referred to as oxides) for the simultaneous immobilization of arsenic (As), cadmium (Cd), and antimony (Sb) in soils procured from 16 contaminated industrial sites. Our findings unveiled that Ca-oxides initially showed excellent immobilization performance for As and Sb within 7 days but experienced substantial mobilization by up to 71 and 13 times within 1 year, respectively. In contrast, the efficacy of Cd immobilization by Ca-oxides was enhanced with the passage of time. Fe- and Mg-oxides, which primarily operate through encapsulation or surface complexation, exhibited steady immobilization performances over time. This reliable and commendable immobilization effect was observed across distinct soils characterized by varying physicochemical properties, including pH, texture, CEC, TOC, and EC, underscoring the suitability of such amendments for immobilizing metal(loid)s in diverse soil types. MgO, in particular, displayed even superior immobilization performance over time, owing primarily to gradual hydration and physical entrapment effects. Remarkably, Mg-Al LDHs emerged as the most effective candidate for the simultaneous immobilization of As, Cd, and Sb. The results obtained from this study furnish valuable data for future investigations on the immobilization of metals and metalloids in industrial soils. They enable the projection of immobilization performance and offer practical guidance in selecting suitable amendments for the immobilization of metal(loid)s.

Keywords: Aging; Heavy metal; Industrial site; Iron oxides; LDHs; Soil remediation.